It has been the practice to use as standard neck ring equipment for champagne finishes a two-piece construction consisting of a vertically split neck ring and plunger. This construction is illustrated in FIGS. 1 and 2 of the accompanying drawings. With such a construction, a finish such as is shown in FIG. 3(a) is produced where a vertical split line or seam is formed that extends up the outside of the container finish and extends over the top sealing surface terminating where the neck ring meets the plunger.
In order to eliminate this split line or seam in the top of the finish, it has been necessary to subject the finish to a gas flame or to what is termed "fire polishing" to, in effect, smooth the top of the finish by melting the seam line and having it blend into the surrounding glass.
This involves an after-forming process that is costly to perform from the standpoint of time and fuel costs in assuring effective treatment.
Furthermore, the rounded configuration of the prior art champagne finish also produced an annular ring of glass where the plunger and neck ring met. This would contribute to a situation where, if natural cork were being used to seal the bottle after filling, frequently the annular ring would tend to have an outer portion "stripped" by engaging this annular protruding ring that can often be fairly sharp. It should be kept in mind that the natural corks that are used are intended to be significantly compressed as they are forced into the container neck to effect a good, gas tight seal. Champagne, of course, is bottled with fairly high carbonation and the included gases exert a significant internal pressure on the cork.